Environmental Engineering Reference
In-Depth Information
greenhouse gases by a large amount compared with gas-
oline or diesel fuel on an equivalent energy basis.
A second way is to compare the total energy used to
make ethanol to the energy content of the ethanol itself.
Here, too, only sugarcane gives a signi
t.
A third way looks at costs relative to gasoline. A gallon
of ethanol contains less energy than a gallon of gasoline,
and costs should be compared on an equal energy basis. It
takes
cant bene
gallons of ethanol to equal the energy in a gallon
of gas so be careful about comparing costs. Prices are
volatile as the oil prices and ethanol feed stocks move up
and down. On this ground, ethanol from corn today is a
loser while sugarcane ethanol is a winner all of the time.
Current US law requires that ethanol be blended in
with gasoline. The ethanol mandate dates originally to
the Farm Bill of
.
, superseded by the Energy Policy
Act of
, in turn superseded by the Energy Inde-
pendence and Security Act (EISA) of
[
]. The
newest law set goals of
billion gallons of ethanol to
be used in the year
and
billion gallons in
.
It de
nes conventional biofuels as those derived from
cornstarch. New ethanol factories have to have a reduc-
tion in greenhouse gas emissions of at least
% com-
pared with conventional motor fuel. The Environmental
Protection Agency (EPA) can reduce this requirement to
as low as
%
goal is not feasible. There is already an argument over
what to include in counting the greenhouse gas emission
from ethanol. Including the effect of land-use changes
makes it very dif
% if it determines that meeting the
%
reduction standard. I would guess that the goal will be
reduced for most factories.
cult for ethanol to meet the
